文章摘要
李敏,翟文建,李开文,赵焕,王晓瑜,田晓敏,裴玉华.北秦岭双龙-夏馆地区镁铁质麻粒岩地球化学、变质演化及其对岛弧环境的限定[J].矿产勘查,2021,12(2):187-199
北秦岭双龙-夏馆地区镁铁质麻粒岩地球化学、变质演化及其对岛弧环境的限定
Geochemistry and metamorphic evolution of mafic granulite in Shuanglong-Xiaguan area, North Qinling:Constraint on the formation in island-arc setting
投稿时间:2020-10-28  
DOI:
中文关键词: 镁铁质麻粒岩  地球化学  P-T轨迹  变质演化  构造环境  双龙-夏馆地区  北秦岭
英文关键词: mafic granulite, geochemistry, metamorphic P-T path, metamorphic evolution, tectonic setting, Shuanglong-Xiaguan area, North Qinling
基金项目:河南1∶5万二郎坪幅等三幅区域地质矿产调查项目(编号:DD20160043-03)、中条-熊耳山成矿区地质矿产调查(编号:DD20160043)和河南省地质调查院青年科技创新基金项目(编号:豫科创[2019]KC-04)联合资助。
作者单位
李敏 河南省地质调查院,河南 郑州 450001
河南省金属矿产成矿地质过程与资 源利用重点实验室,河南 郑州 450001 
翟文建 河南省地质调查院,河南 郑州 450001
河南省金属矿产成矿地质过程与资 源利用重点实验室,河南 郑州 450001 
李开文 河南省地质调查院,河南 郑州 450001
河南省金属矿产成矿地质过程与资 源利用重点实验室,河南 郑州 450001 
赵焕 河南省地质调查院,河南 郑州 450001 
王晓瑜 河南省地质调查院,河南 郑州 450001 
田晓敏 河南省地质调查院,河南 郑州 450001 
裴玉华 河南省地质科学研究所,河南 郑州 450001 
摘要点击次数: 235
全文下载次数: 122
中文摘要:
      北秦岭双龙-夏馆地区出露有镁铁质麻粒岩,其岩石成因及构造意义不甚清楚,该文对其进行了矿物学、变质温压条件和岩石地球化学研究。结果表明,研究区镁铁质麻粒岩变质演化经历了3个变质阶段:峰期麻粒岩相变质阶段(M1)矿物组合为石榴子石(Grt)+单斜辉石(Cpx)+斜方辉石(Opx)+斜长石(Pl1)+石英(Qtz)+角闪石(Hb1)(高Ti)+钛铁矿(Ilm);退变角闪岩相阶段(M2)矿物组合为角闪石(Hb2)+斜长石(Pl2)+榍石(Sph2);晚期绿片岩相阶段(M3)以形成低温退变质矿物组合绿泥石(Chl3)+黑云母(Bi3)特征。峰期变质条件为T=807~890℃,P=7.8~8.1 kbar,其变质演化过程具有逆时针型P-T轨迹,为中低压麻粒岩。地球化学数据显示原岩具有拉斑质岩石的地球化学特征,SiO2、Al2O3、P2O5含量相对较低,TFeO、CaO、MgO含量相对较高。镁铁质麻粒岩稀土元素配分模式为轻稀土元素弱富集、重稀土元素相对平坦的右倾型,Eu异常不明显(δEu=0.78~0.94)。岩石富集K、Th、Ba等大离子亲石元素,亏损Nb、Hf、P等高场强元素的特点,并且Ti具弱的负异常,原岩兼具E-MORB(富集型洋中脊玄武岩)和IAB(岛弧玄武岩)的特征,形成于与俯冲有关的岛弧环境。
英文摘要:
      Mafic granulites occur on Shuanglong-Xiaguan area of North Qinling, but their petrogenesis and structural significance are not clear, therefore the mineralogy, metamorphic P-T condition and rock geochemistry are studied in this paper.The results show that the metamorphic evolution of mafic granulite in this investigated area has experienced three metamorphic stages:peak granulite facies metamorphic stage (M1) mineral assemblage is Grt+ Cpx + Opx+Pl1+ Qtz+ Hb1+ Ilm, Retrograde amphibolite facies stage (M2) mineral assemblage is Hb2+Pl2+Sph2, and late greenschist facies stage (M3) is characterized by low temperature retrograde metamorphic mineral assemblage chl3 + Bi3.The peak metamorphism condition is T = 807-890℃, P = 7.8-8.1 kbar, and its metamorphic evolution process has a anticlockwise P-T evolution track, indicates that it is middle-low pressure granulite.The geochemical data show that the protolith has the geochemical characteristics of tholeiitic rocks.The contents of SiO2, Al2O3 and P2O5 are relatively low, while the contents of TFeO, Cao and MgO are relatively high.The REE distribution pattern of mafic granulite is right dipping type with weak LREE enrichment and relatively flat hree.Eu anomaly is not obvious (δEu =0.78-0.94).The rocks are enriched in large ion lithophile elements such as K, Th, Ba, and depleted in high field strength elements such as Nb and Hf and P, and Ti has weak negative anomaly.The protolith has the characteristics of E-MORB (enriched mid ocean ridge basalt) and IAB (island arc basalt), and formed in the island arc environment related to subduction.
查看全文   查看/发表评论  下载PDF阅读器
关闭